Backtest-only gate (no forward wiring) for the China/India diversifier question,
decided from ~7y of real Yahoo data. Reuses the SSOT marginal_sharpe primitive +
multistrat.book_series verbatim; cost model = max(vol-norm re-sizing turnover,
monthly-rebalance floor) so a quiet co-crasher can't survive at ~0 modeled cost.
Result (10bp UCITS, 2019-08..2026-07): CNYA.L marginal Sharpe -0.099, NDIA.L
-0.048 — both co-crash the book (+0.23 corr) and worsen with cost. KILL both:
the accessible UCITS wrapper carries EM beta, not the mainland inefficiency
(direct A-shares/NSE closed to the EU-retail entity). Same co-crash death as VRP
and unlock. Do NOT wire the em_asia forward sleeve.
Gate is generic — reusable for any single-instrument diversifier candidate.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Jeroen Grusewski
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